The mining industry is of great importance for the economy of many countries. Nevertheless, it is common knowledge that tailings, the material left over after the process of separating the valuable fraction from the uneconomic fraction of ores, are responsible for significant issues for the mining activities—both environmentally and economically. The incorporation of tailing in productive processes may reduce costs and open up new business opportunities, further it may reduce the volume of extraction of raw materials, preserving the limited natural resources.
Currently, it is also known that mining companies use polymeric sheets in their facilities, as in coating silos, channel of transfer conveyor belts, scrapers, screen rollers, plows, mixers, pellet discs, transfer points of ore and pellet, among other applications.
Nowadays, there are critical company concerns about the environment. There is an incessant quest for technologies in order that products and byproducts return to a closed sustainable cycle.
Recycling is a transformation opportunity of an important source of expenses into a revenue source or, at least, to reduce the deposition expenses.
Recycling processes for plastics or polymeric materials are known in the art and seek to reuse these materials in order to obtain recycled raw material that can return to the polymer manufacture production chain or can be used for other purposes with commercial interests.
The polyethylene (PE), is chemically the simpler polymer and is represented by the chain (CH2-CH2)n. Due to its high worldwide production, it is also cheapest, being one of the most common types of plastic. It is obtained by ethylene polymerization (chemical formula CH2=CH2) which derives its name. The polyethylenes can be classified as PEBD, HDPE, PELBD, UHMWPE or PEX.
The High Density Polyethylene (HDPE, in Portuguese known as PEAD) presents density greater than 0.941 g/cm3. PEAD has a low level of branching, with high density and high intermolecular forces. The high-density polyethylene (HDPE) is the second most recycled resin in the world. Applications for recycled HDPE have become more frequent and may be used to: flooring (mixed with asphalt), wood plastic, construction, automotive industry, manufacturing of industrial packaging, plastic bags, buckets, cards, etc. Recycled HDPE has also been applied in construction, to build structural elements.
UHMWPE is the acronym for Ultra High Molecular Weight Polyethylene. The extremely high molecular weight provides to this engineering plastic excellent mechanical properties, such as high wear resistance by abrasion, high impact resistance and low coefficient of friction.
In an attempt to find alternative ways of developing materials, the number of studies with composites materials involving tailing has intensified increasingly. The positive results have encouraged research centers and companies to invest in developing new composites and improving processing techniques to manufacture products with aggregated mechanical properties and economic viability.
The production of these composites is presented as an alternative for recycling, in view of the possibility to reuse some industrial tailing of interest. The manufacturing processes for obtaining composites usually involve extrusion or pressing routes.
Composites are materials designed to combine desirable features from two or more materials of different nature. Particulate materials can be conceptualized as particulate fillers, usually inorganic substances which are added to the polymer matrix, in order to alter their physical and mechanical properties. For some time this kind of material was employed in composites production with the primary function of reducing cost of the final product, since they diminished the amount of polymer used. However, over time, other functions have been attributed to these materials. Various types of particulate materials have been used as fillers in polymeric composites, such as calcium carbonate, talc, clay and micro spheres of glass, influencing positively in properties such as creep resistance, heat distortion temperature (HDT), thermal conductivity, and hardness, stiffness and wear resistance.
The present invention relates to a composite material that comprises polyethylenes and ore tailing. Preferably, the present invention relates to a composite material that comprises UHMWPE and iron ore tailing.
The technology that utilizes the coupling of additives in a polymer matrix in order to obtain improvements in the mechanical properties of new composites is becoming known in the prior art and particulate materials are already used for the production of polymeric composites.
Inorganic materials, like silicates, ceramics, talc, glass beads and inorganic fibers have already been described in the manufacture of commercial and engineering composites for many kinds of applications, according to the obtained properties.
Wang Lixin (CN103044926 and CN103044927) discloses an oil seal rubber material for automobile engines and a piston rubber material for mud pumps, which were produced with polymers, modified iron ore tailing powder, silica, carbon blacks, and tree ashes, among other components. The rubber materials which are disclosed by these inventions present good mechanical properties and resistance to high/low temperature, oil, solvents and chemicals, but they are made out of a combination of many different types of filler and directed to the automobilist industry.
The present invention relates to a new composite material that comprises polyethylenes, preferably Ultra High Molecular Weight Polyethylene (UHMWPE) with a reinforcement load of iron ore, preferably iron ore tailing. The present invention composite may be used for the manufacture of sheets or plates aiming to substitute the polymeric sheets usually made solely with HDPE and UHMWPE. The present invention also represents a useful and ecological application for formerly unused and pollutant byproducts resulting from ores pelletizing processes (especially iron ore pelletizing processes).
The present invention composite material reuses tailings of industrial plant, causing significant cost reductions in mining and significant environmental advantages because it allows recycling waste polymers too, which would take hundreds of years to decompose. It also surprisingly presents improved properties such as creep resistance, stiffness and wear resistance, which are important properties for substituting polymeric sheets used in mining companies facilities.